<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .father {
            width: 100%;
            height: 60vw;
            background-color: red;
        }

        div {
            width: 30%;
            height: 30%;
            background-color: blue;
            float: left;
            margin: 1%;
        }
    </style>
</head>

<body>
    <div class="father">
        <div>1</div>
        <div>1</div>
        <div>1</div>
        <div>1</div>
        <div>1</div>
        <div>1</div>
        <div>1</div>
        <div>1</div>
        <div>1</div>

    </div>
</body>

</html>